A ship propulsion apparatus or system is used in a powerboat, a rubber boat, a sailboat, or the like. The ship propulsion apparatus will employ an engine or an electric motor to be a power device. No matter which power device is employed by the ship propulsion apparatus, the power device or other component generates heat. If the heat is not discharged timely, the temperature of the power device or other element may increase, which may influence the performance. Overheating may cause permanent damage to the ship propulsion apparatus.